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'Fail Safe' mode?

T

Trackrod996

New member
When I started my car about a month ago, after a break of a few weeks in the garage, it fired up OK, I left it to run for a few minutes, but when I went to drive it out of the garage it had no power and wouldn't rev over 1500, but continued ticking over just fine. I switched off and restarted, after which it was OK, took it for a quick blast, then parked it up again.
Went to start it yesterday, but battery was too weak to fire it up, so I left it trickle charging for 24 hours. Fired up fine this afternoon (no lengthy warm-up) but as soon as I got it on to the road it lost power and went onto it's 1500 rev max. mode again. I stopped and fired it up again, after which it got me about a mile up the road, when it happened again, but would not drive normally this time, so I limped home and have now disconnected the battery and put it on a proper charge. Am I right in assuminmg that this is some kind of fail-safe mode for a low battery or such? If not, any ideas? All gauges showing correct figures.
Also, when I disconnected the battery, the alarm continued for a few more seconds. How is this so?
 
It doesn't sound like normal behaviour to me, and I'm not aware of any fail-safe mode for the DME. Best bet is to see what happens now you have disconnected the battery, which will reset the DME. If it happens again, the only thing to do is to get a diagnostic check done with a Porsche tester.

It is normal for the alarm siren to go off when you disconnect the battery. The siren has a backup battery built-in. The way to stop it happening is to switch the ignition on, but don't start the engine, before you disconnect the negative terminal of the battery.
 
Note on some models , not sure on 996 but definately on 986 when reconnecting the battery you should re-adapt the DME this is partly done by by switching on the igntion for 1 minute then switching of for at least 10 sec then start the car. This allow values to be stored for the throttle adjusting unit.
I would be inclined to swap to a good known battery and see if this cures your problem.
 
The procedure you show can be performed at any time but there are other conditions which must be met. This works with all eGas 996's.

I think that disconnecting the battery will reset the adaption values regardless of the other conditions,

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That's interesting Richard the conditions aren't listed in the 986 manual(least not in the battery change bit ). Blomin dificult with a battery change in the snow to get temps over 10deg C .[:D]
 
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